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Surfactant Systems (surfactant + system)

Distribution by Scientific Domains

Chemistry	53%
Medical Sciences	20%

Selected Abstracts

Surfactant Systems: A Survey of the Transcontinental Gas Pipeline from Houston to New Jersey

ARCHITECTURAL DESIGN, Issue 6 2005
Petia Morozov
Abstract The Transcontinental Pipeline, Transco, is a 10,560-mile line that traverses the US, transporting natural gas from its source in the Gulf of Mexico to the East Coast. Petia Morozov describes the postwar engineering feat that made the pipeline a reality, and also reveals the web of myriad agreements, with often diametrically opposed parties or interests, that support its rights of way and management. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Micelle-to-Vesicle Transition Induced by Organic Additives in Catanionic Surfactant Systems

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2006
Haiqing Yin
Abstract A micelle-to-vesicle transition (MVT) induced by the addition of a series of apolar hydrocarbons (n -butylbenzene, n -hexane, n -octane, and n -dodecane) to the catanionic surfactant system n -dodecyltriethylammonium bromide/sodium n -dodecylsulfate (DTEAB/SDS) has been investigated for the first time by means of rheology and turbidity measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Interestingly, a MVT can take place within certain micellar regions, which are dependent on the structure and chain length of the hydrocarbon. However, these hydrocarbons are unable to induce a MVT in another catanionic surfactant system, namely, n -dodecyltriethylammonium bromide/sodium n -dodecylsulfonate (DTEAB/SDSO3), in which the molecular interactions are weaker than in the DTEAB/SDS system. On the other hand, polar additives, such as n -octanol and n -octylamine, exhibit much higher efficiency and activity in inducing MVT than hydrocarbons in both DETAB/SDS and DTEAB/SDSO3. Moreover, DLS, TEM, and time-resolved fluorescence quenching (TRFQ) results demonstrate that the ratio of vesicles to micelles in the system can be actively controlled by addition of polar additives. Possible mechanisms for the above phenomena are presented, and the potential application of controllable micelle/vesicle systems in the synthesis of tailored bimodal mesoporous materials is discussed. [source]

Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritation

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004
L. Rhein
Salicylic acid (SA) is a beta-hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3,4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e. epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 h. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably low alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin. [source]

Determination of phenol using an enhanced chemiluminescent assay

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 1 2003
A. D. Ilyina
Abstract Enhanced chemiluminescence (ECL) describes the phenomenon of increased light output in the luminol oxidation reaction catalysed by horseradish peroxidase (HRP) in the presence of certain compounds, such as para -iodophenol. In this work, the effects of phenol on the para -iodophenol-enhanced HRP-catalysed chemiluninescent reaction intensity in an aqueous buffer (Tris,HCl buffer, pH 8.5) and in a surfactant,water,octane mixture were compared. Preincubation of HRP at low phenol concentrations stimulated the chemiluminescent intensity in the assay performed in an aqueous buffer, but did not have significant effect in the sodium bis(2-ethylhexyl)sulphosuccinate) (Aerosol OT, AOT) applied system. It was also observed that HRP preincubation with phenol concentration higher than 0.003,mg/mL produced an inhibitory effect on the enzyme activity for both assay systems. Only an inhibitory effect of phenol on the chemiluminescent intensity in the surfactant system in octane (as organic solvent) was observed. Three assays were developed to determine phenol concentration in water and in an organic solvent mixture. The detection limits were 0.006, 0.003 and 0.0005,mg/mL, respectively, for the buffer-containing system, the AOT-applied system with phenol standard solutions in water and for the AOT-applied system with phenol standard solutions in octane. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Micelle-to-Vesicle Transition Induced by Organic Additives in Catanionic Surfactant Systems

Highly Ordered Mesoporous Carbonaceous Frameworks from a Template of a Mixed Amphiphilic Triblock-Copolymer System of PEO,PPO,PEO and Reverse PPO,PEO,PPO

CHEMISTRY - AN ASIAN JOURNAL, Issue 10 2007
Yan Huang
Abstract A series of highly ordered mesoporous carbonaceous frameworks with diverse symmetries have been successfully synthesized by using phenolic resols as a carbon precursor and mixed amphiphilic surfactants of poly(ethylene oxide)- b -poly(propylene oxide)- b -poly(ethylene oxide) (PEO,PPO,PEO) and reverse PPO,PEO,PPO as templates by the strategy of evaporation-induced organic,organic self-assembly (EISA). The transformation of the ordered mesostructures from face-centered (Fdm) to body-centered cubic (Imm), then 2D hexagonal (P6mm), and eventually to cubic bicontinuous (Iad) symmetry has been achieved by simply adjusting the ratio of triblock copolymers to resol precursor and the relative content of PEO,PPO,PEO copolymer F127, as confirmed by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and nitrogen-sorption measurements. The blends of block copolymers can interact with resol precursors and tend to self-assemble into cross-linking micellar structures during the solvent-evaporation process, which provides a suitable template for the construction of mesostructures. The assembly force comes from the hydrogen-bonding interactions between organic mixed micelles and the resol-precursor matrix. The BET surface area for the mesoporous carbonaceous samples calcined at 600,°C under nitrogen atmosphere is around 600,m2,g,1, and the pore size can be adjusted from 2.8 to 5.4,nm. An understanding of the organic,organic self-assembly behavior in the mixed amphiphilic surfactant system would pave the way for the synthesis of mesoporous materials with controllable structures. [source]

Structure and physico-chemical properties in mixed aqueous solution of sodium alkylcarboxylate-alkyltrimethylammonium bromide

CHINESE JOURNAL OF CHEMISTRY, Issue 3 2000
Huang Jian-Bin
Abstract The physico-chemical properties of organized assemblies (micelle or vesicle) from sodium alkylcarboxylate - alkyltrimethyl -ammonium bromide mixture have been investigated systematically. In different mixed cationc-anionic surfactant systems, micelles and vesicles can coexist or be transformed into each other on different conditions. The experimental results are explained prelimilarily from the viewpoint of molecular packing geometry. The solubilization of organic compound in the mixed surfactant system was also studied in detail. [source]

NMR studies of surfactants

CONCEPTS IN MAGNETIC RESONANCE, Issue 2 2004
Olle Söderman
Abstract Surfactant molecules are amphipathic and posses complicated solution chemistry and self-assembly properties. In addition to being of enormous practical significance, the physical characterization of surfactant systems presents a rich area of condensed matter physics. This article focuses on the application and interpretation of the commonly used NMR approaches for probing these systems. In particular, the use of NMR relaxation, diffusometry and, more briefly, electrophoretic NMR to determine characteristics such as micellar size and structure, ion-binding and solubilization are considered. The application of these NMR techniques is illustrated by a number of pertinent examples. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 23A:, 121,135, 2004. [source]

Monomeric and polymeric anionic gemini surfactants and mixed surfactant systems in micellar electrokinetic chromatography.

ELECTROPHORESIS, Issue 2 2005
Part II: Characterization of chemical selectivity using two linear solvation energy relationship models
Abstract Sodium di(undecenyl) tartarate monomer (SDUT), a vesicle-forming amphiphilic compound possessing two hydrophilic carboxylate headgroups and two hydrophobic undecenyl chains, was prepared and polymerized to form a polymeric vesicle (i.e., poly-SDUT). The anionic surfactants of SDUT and poly-SDUT (carboxylate head group) and sodium dodecyl sulfate, SDS (sulfate head groups) as well as mixed surfactant systems (SDS/SDUT, SDS/poly-SDUT, and SDUT/poly-SDUT) were applied as pseudostationary phases in micellar electrokinetic chromatography (MEKC). Two linear solvation energy relationship (LSER) models, i.e., solvatochromic and solvation parameter models, were successfully applied to investigate the effect of the type and composition of pseudostationary phases on the retention mechanism and selectivity in MEKC. The solvatochromic and solvation parameter models were used to help understand the fundamental nature of the solute-pseudostationary phase interactions and to characterize the properties of the pseudostationary phases (e.g., solute size and hydrogen bond-accepting ability for all pseudostationary phases). The solute types were found to have a significant effect on the LSER system coefficients and on the predicted retention factors. Although both LSER models provide the same information, the solvation parameter model is found to provide much better results both statistically and chemically than the solvatochromic model. [source]

Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritation

SN2 reaction of a sulfonate ester in the presence of alkyltriphenylphosphonium bromides and mixed cationic-cationic systems

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2006
Michael M. Mohareb
Abstract The effects of alkyltriphenylphosphonium bromides (CnTPB, n,=,10, 12, 14, 16) on the rates of SN2 reactions of methyl 4-nitrobenzenesulfonate and bromide ion have been studied. Observed first-order rate constants are significantly higher than those found for other cationic surfactants for the same reaction. The results have been analyzed by the pseudophase model of micellar kinetics and show true micellar catalysis in the sense that second-order micellar rate constants are higher than the second-order rate constants in water. An attempt has also been made to investigate mixed cationic,cationic surfactant systems with respect to observed rates and pseudophase regression parameters. In addition, modeling of some cationic head groups has illustrated possible differences in head group charges and counterion interactions that may prove kinetically relevant. Copyright © 2006 John Wiley & Sons, Ltd. [source]

A comparative study of transformation of micellar structures in CTAB and TTAB binary systems using Positron Lifetime Spectroscopy

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2009
R. Yadav
Abstract The micellar structures of cetyl-tri-methyl ammonium bromide (CTAB) and its homologues have been investigated employing several conventional techniques. However, due to lack of sensitivity inherent in these techniques and the perturbation introduced by the probe, the detailed structures of the aggregates in the so-called single phase regions of these systems are far from being fully understood. Positron has been found to be a useful non-destructive probe for investigating micellar structures in surfactant systems [1-3] The present study is an effort to get a better insight into the micellar structures and their transformations in CTAB and TTAB aqueous binary systems Positron lifetime spectroscopy has been employed to study these systems covering a wide range of surfactant concentrations. A comparative study of the results obtained for the two surfactant systems have been discussed in this paper. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Structure and physico-chemical properties in mixed aqueous solution of sodium alkylcarboxylate-alkyltrimethylammonium bromide

Sharpless Asymmetric Dihydroxylation of Olefins in WaterSurfactant Media with Recycling of the Catalytic System by Membrane Nanofiltration

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008

Abstract This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant system as reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5,mM sodium cholate aqueous solution, using N -methylmorpholine N -oxide (NMO) as co-oxidant was selected as model system to evaluate the feasibility of recycling the Sharpless catalytic system by nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic system and surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields. [source]